Hungarian Defence Minister Tibor Benko signed a letter of intent to buy Advanced Medium-Range Air-to-Air Missiles (AMRAAM) with US Ambassador David Cornstein, according to Hungary's MTI news agency.

The purchase of the mid-range missile system made by US firm Raytheon Technologies is NATO member Hungary's "largest-ever defence procurement" from the US, Cornstein said in a statement.

The approximately $1 billion (850,000 euros) acquisition will "overhaul and modernise Hungary's air defence capabilities and allow it to transition away from its current legacy Soviet system," he said.

Prime Minister Viktor Orban's government has been hiking spending on the previously underfunded military in recent years.

The proportion of Hungarian GDP spent on defence rose from 0.95 percent in 2013 to 1.21 percent in 2019.

But US Secretary of State Mike Pompeo left out Budapest from the itinerary of a tour of Central European countries this week to discuss US troop deployments, as well as Chinese and Russian influence in the region.

Orban, a vocal supporter of US President Donald Trump, has long forged close ties with both Moscow and Beijing, part of what he calls a "pragmatic" foreign policy.

He has also signed a Chinese-backed high-speed rail infrastructure project and despite US protests involved Chinese telecoms giant Huawei in rolling out Hungary's high-speed 5G mobile phone network.