Until the Russian attack Sunday on Ukrainian vessels in the Black Sea, the White House and the Kremlin had at least been agreed on one thing: the agenda for Saturday’s scheduled face-to-face between U.S. President Donald Trump and his Russian counterpart Vladimir Putin, their second summit meeting.

Arms control, security issues as well as the Middle East and North Korea were all set to figure prominently, senior U.S. and Russian aides told reporters in the run-up to the meeting.

Russian officials say the Kremlin had earmarked as their key issue Trump’s recent decision to abandon a landmark Cold War-era agreement prohibiting the U.S. and Russia from possessing ground-launched short-range nuclear missiles.

For the White House, securing a public commitment from the Russians to enforce United Nations sanctions on North Korea before next month’s planned summit between Trump and North Korean leader Kim Jong Un was a key objective, according to U.S. officials.

But analysts say the Russian attack on three Ukrainian vessels risks shifting the dynamics of Saturday’s planned two-hour face-to-face between Trump and Putin on the sidelines of the G20 summit in Argentina, with the U.S. leader being urged to take a tough line that might imperil his overall determination to improve U.S.-Russian relations.

Trump suggested Tuesday he might cancel the meeting after Russian ships opened fire on and seized the Ukrainian ships near Crimea. But on Thursday he indicated the meeting will go ahead.

“I probably will be meeting with President Putin. We haven’t terminated that meeting. I was thinking about it, but we haven’t. I think it’s a very good time to have the meeting,” he told reporters at the White House.

Kremlin spokesman Dmitry Peskov told reporters Wednesday in Moscow the White House hadn’t indicated to the Kremlin the meeting wouldn’t be held.

“We don’t have to agree on all issues, which is probably impossible, but we need to talk. It’s in the interests of not only our two countries, it’s in the interests of the whole World,” Peskov said.

Asked what would be discussed, he said, “First of all, questions related to bilateral relations, we need to think about how to start talking on matters of bilateral relations, on matters of strategic security and disarmament and on regional conflicts.”

Earlier this week John Bolton, the U.S. National Security Adviser, said Trump would discuss security, arms control and regional issues with Putin.

“I think it will be a continuation of their discussion in Helsinki,” he said, referring to the first summit meeting between the two leaders held in Finland in July, when they met for more than two hours with only their translators present.

The Helsinki sit-down prompted widespread criticism of Trump from across the U.S. political spectrum, with Republican and Democrat lawmakers expressing dismay at what they saw as the U.S. leader’s amplifying of Putin denials of Russian meddling in the 2016 U.S. presidential elections.

Bolton did not confirm whether the naval clash in the Kerch Strait, a shared Russian-Ukrainian waterway linking the Black Sea with the Sea of Azov, would be on the table. But it is hard to see how it won’t be amid Western clamor about what U.S. Secretary of State Mike Pompeo has labelled a “dangerous escalation and a violation of international law.”

State Department Spokeswoman Heather Nauert said Washington wanted to see tougher enforcement of sanctions against Russia as a consequence of the Russian action, the first time the Kremlin has staged open aggression against Ukraine since Putin annexed Crimea four years ago and launched a destabilization campaign in Ukraine’s Donbas region.

German chancellor Angela Merkel is expected to address the Kerch incident at the G20 meeting before the Trump-Putin sit-down.

Ukrainian president Petro Poroshenko piled pressure Thursday on the G20 by calling for a tough collective response to Russia, saying he fears Moscow intends broader military action against his country.

European Union hawks have called for more sanctions to be imposed on Russia, although diplomats say with the bloc already divided over policy towards Russia, it is unlikely that will happen swiftly without a strong lead from Washington.

Trump waited more than 24 hours after the maritime clash before he commented on the incident, prompting criticism, once again that he was going lightly on his Russian counterpart. But once he did address the clash, his irritation was clear.

“I don’t like that aggression. I don’t want that aggression at all,” he told the Washington Post.

Steven Pifer, a former U.S. ambassador to Ukraine and now an analyst at the Washington-based Brookings Institution said if Trump “does not raise the question of the Russian conflict against Ukraine … the Russian would calculate the President is weak on this issue.

“That’s going to be bad for Ukraine, but also bad for American foreign policy,” he told VOA.