BRUSSELS — The European Union's top diplomat said Monday that the world is going through a time of chaos and that the 28-nation bloc must work more closely with international partners as the multilateral system comes under threat.

In a speech to EU ambassadors laying out her vision for the year to come, EU foreign policy chief Federica Mogherini said that "the whole world is going through a moment of chaos, and the question is: is it a moment or is it a long-term trend?"

"The very idea of multilateralism is being challenged," Mogherini said.

While she didn't mention the U.S. or President Donald Trump directly, Mogherini underlined the importance of the Iran nuclear agreement and the global climate change pact rejected by Trump. She also referred to the central role of the World Trade Organization, whose rules are being tested by Trump's policies.

"No great power is really great enough in the world of today," she said.

Mogherini urged the ambassadors to reassure partners — ranging from Canada, Australia, New Zealand, Japan, South Korea and all of Africa — that "Europe is not withdrawing from the world stage. On the contrary, we will be even more engaged in the year ahead."

She said the European Commission has proposed increasing the budget of the bloc's External Action Service — essentially a foreign office with about 140 delegations worldwide — by around 30 percent to show that "we are ready to play a role in the world, with our principles, with our values, with our policies, but also with our resources."

With a combined population of around 500 million people, the EU is the world's biggest trading bloc and a top aid donor.