Armero courted attention after playing a starring role in Colombia's run to the World Cup quarter-finals.
Milan are reported to be on the verge of securing the 27-year-old on an initial loan from Serie A rivals Udinese, and appear to have moved a step closer to completing a deal.
"Waiting for #Armero... Pablo [has] arrived at the Malpensa Airport. Stay tuned," Milan posted on their official Twitter account.
Armero, who had been co-owned by Napoli until Udinese bought his full rights in June, spent the second half of last season on loan at Premier League side West Ham.
However, he had a largely forgettable time at Upton Park and made just five appearances for Sam Allardyce's side.
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