The Hungarian army has begun exercises to prepare for a possible future role in guarding the southern border to try to stem the influx of refugees.
Budapest plans to send soldiers to help police at the border where thousands of migrants arrive from Serbia every day.
A new razor-wire barrier is already being built along the frontier.
Meanwhile, the Hungarian parliament is expected to vote on stricter border controls later this month.
Authorities have been told to expect 40,000 more migrants by next week.
Many of them are fleeing conflicts in countries like Syria and Libya and are trying to travel through Hungary to Germany, Austria and Sweden – wealthier EU nations with more liberal asylum laws.
The Hungarian army launched the Decisive Action exercises on September 9 to prepare for its possible new role, pending a vote in parliament.
“It is our job to make sure Hungary is defended,” General Tibor Benko said.
Hungary has recently completed a 110 mile razor-wire fence along its border with Serbia, and is building an additional barrier.
PM Viktor Orban this week pledged to speed up the construction of the new barrier.
“Everyone has to get ready to do intensive work in the coming weeks,” he was quoted as saying.
However, the measures have so far failed to stop thousands of people getting into Hungary from Serbia.
Hungary has become a key point on the journey north for the refugees, with more than 150,000 people arriving this year.
A surge of refugees fleeing conflict and hardship in Africa and the Middle East has pushed north through Europe over the past few weeks.