Bill Clinton, the U.S.’s 42nd president, recalled at a New York conference this week the moment he realized Russian president Vladimir Putin had designs to take over its neighbor.

Appearing alongside his wife Hillary at an event in New York, Clinton said Putin confronted him over a deal made with former Russian president Boris Yeltsin.

The U.S.-brokered deal saw Russia pledge to respect Ukrainian territory in exchange for Kyiv relinquishing its nuclear power.

Clinton said Putin told him in 2011 he didn’t agree with the deal: “He said… ‘I don’t agree with it. And I do not support it. And I am not bound by it.’ And I knew from that day forward it was just a matter of time.”

It is not the first time Clinton has reflected on the deal made in 1994. In April he revealed he has a “personal stake” in the Ukraine war, as he felt “terrible” for his part in persuading the country to give up its nuclear weapons.

The agreement also set the stage for Ukraine’s later inclusion in the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) as a non-nuclear-weapon state.

Clinton told Irish broadcaster RTE: “None of them [Ukrainians] believed that Russia would have pulled this stunt if Ukraine still had their weapons.”

Clinton’s mistrust of Putin was echoed by his wife Hillary, the presidential hopeful of 2016 who was defeated by Donald Trump.

“[Putin] is in what he views as a righteous struggle to undermine Western democracy and reinstitute, as much as he can, the Russian empire,” she said. “So he’s not going to stop.”

During their appearance, the Financial Times reported, the pair urged Western forces to continue to support Ukraine.

It’s an argument Hillary Clinton has made in the past, telling nonprofit Vital Voices: “I think we need to be very clear in sending a message to Putin that we’re going to do everything we can to make sure he does not succeed in Ukraine.

“And, at some point, given the losses in his military, given the losses of his military leadership, given the turmoil within his intelligence and security forces, because they told him what he wanted to hear, and it didn’t work out, I think that there’s more to be seen about what happens inside the Kremlin as this unfolds.”

Hillary argued that to bring the issue to a close, Ukraine must either defeat its invaders or at least regain the eastern territories it lost last year.

“They need leverage. I wouldn’t trust him [Putin] at a negotiating table under any circumstances, unless Ukrainians—backed by us—have enough leverage,” she said.

Opening the door for China

Hillary also believes the West’s support of Ukraine has deterred a similar move by Chinese President Xi Jinping: invading Taiwan.

If Putin had invaded Ukraine without consequence, it would have emboldened Ji, she said. Instead, he witnessed sanctions on Russia: “I think before the Russian invasion, there was a good chance he would have moved on Taiwan within two to three years. I think that timetable has been pushed back.”

It was a sentiment echoed this week by Robert O’Brien, a former national security adviser to the Trump administration.

He told Japanese newspaper the Yomiuri Shimbun he believes China intends to invade Taiwan within a year or two, and that the U.S. and Japan need to be proactive in offering support.

If the U.S. and its allies do not “provide Taiwan with the weapons it needs to defend itself, and give it the diplomatic muscle that Taiwan needs to prevent the Chinese from believing that they can invade Taiwan without consequence, we could be in a very dangerous situation in Taiwan,” he warned.