In the first bilateral meeting between the two leaders on Monday, Trump praised the Hungarian leader for his tough stance on immigration, calling him his "twin".

Orban said military cooperation was paramount and Hungary, whose economy has been growing faster than most others in Europe, can now afford to recreate a potent military force.

"There are parts of military development in which we count on the Americans," Orban told Hungarian state radio.

"Critical infrastructure must be protected in case of a military attack, and Hungary's capability in that regard is incomplete. We need mid-range air defence missiles here. The legal procedure to acquire them is proceeding apace."

Orban, whose close ties with President Vladimir Putin's Russia and China have drawn criticism from international partners, and especially Washington, said he wanted to build better ties with all major powers.

"We cooperate with the Chinese and the Russians as well as the Americans ... to be sure, with them (the Americans) we are in a military alliance, therefore those ties are stronger," he said.

He added that he had asked Trump to help start production of natural gas under the Romanian section of the Black Sea, which will be done with participation from Exxon, to provide the only practical alternative to Russian gas.

Senior US lawmakers criticised Orban's visit to the White House last week, blaming him for a "downward democratic trajectory".

Australian Associated Press